1. Field of the Invention
This invention concerns chucks, and more particularly quick-change spindle nose adapters in which a toolholder adjuster nut is gripped by a plurality of radially moveable balls which are locked in gripping relationship by means of an axially reciprocable control sleeve.
2. Description of the Prior Art
A recognized desirable feature of quick-change adapters of the type described above has been a "stay-open" capability for the control sleeve, that is, the control sleeve can be detented in the unlock position so that both hands are available for the handling of heavy toolholder assemblies.
Heretofore, such capability has been provided by axially moveable elements which are engaged by the toolholder assembly so that whenever it is not seated in the adapter, the control sleeve will automatically detent open. Typical arrangements are shown in U.S. Pat. Nos. 2,970,844; 3,552,758; and British Pat. No. 342,678.
These arrangements have, in general, been relatively complicated and have added significantly to the cost of the assembly.
In addition, in removing a toolholder, the toolholder must be advanced at least partially out while the control sleeve is in the unlock position. While the axially moveable element may automatically force the nut out if friction is low, or if the toolholder is relatively unweighty and the installation angle is downward, in some installations the toolholder must be manually advanced in order to lock open the control sleeve.
It is, therefore, an object of the present invention to provide a stay-open capability for such an adapter which is relatively simple and inexpensive to add, and also does not require any handling of the toolholder to actuate.